Achievement - Fish or Cut Bait

Ironforge:

The Gnomish Bait-o-Matic

Buy five (5) Shiny Baubles from Tansy Puddlefizz, who is just inside the building, where you  get the quest.
Buy one (1) hair trigger, which you can buy from the Engineer trainer in Tinker Town.  Then head into the Deeprun Tram and collect three (3) Rat Traps from around the area.  Right click the rat traps and make the Gnomish Bait-o-Matic.  Return to the quest giver.

Achievement - Fish Don't Leave Footprints

This achievement should be one of the first fishing achievements you go for.  This helps you find nodes when fishing, which will come in very handy for all other fishing achievements. Go to Northern Stranglethorn Vale and look for any wreckage in the water.  You will want to fish out of any wreckage until you receive the Weather Beaten Journal.  Once you fish up the journal, click to learn it and you will now have the ability to Find Fish.  You can turn this off and on by clicking on the magnifying glass on your mini map, the same as Find Ore, Find Herbs, etc.

Achievement - The Scavenger

The Scavenger is one of the achievements needed for the fishing meta achievement, Accomplished Angler.  This achievement is relatively easy, requires a little bit of traveling and a little bit of time. If you do not have the achievement, Fish Don't Leave Footprints, I would recommend doing that with this achievement, as you will have to fish out of the same pool.

To complete The Scavenger, you need to fish in each of the following junk nodes: Steam Pump Flotsam, Bloodsail Wreckage, Schooner Wreckage, Waterlogged Wreckage and Floating Wreckage. 

Bloodsail Wreckage:
You can find these nodes south of Booty Bay, or in the bay by Fort Livingston in Northern Stranglethorn Vale.  I would recommend Northern Stranglethorn because it's closer to where you will find Schooner Wreckage.

Schooner Wreckage:
You can find Schooner Wreckage nodes along the West coast of Northern Stranglethorn Vale, in the Vile Reef.

Floating Wreckage:
You can find Floating Wreckage along the Eastern coast of Blasted Lands and Swamp of Sorrows.  I just flew from STV to Blasted Lands and flew along the coast until I found a Floating Wreckage node.

Waterlogged Wreckage:
Waterlogged Wreckage nodes can be found in Western Plaguelands in the water surrounding Sholomance.

Steam Pump Flotsam:
These nodes are the only ones that can't be found in Eastern Kingdoms.  The only place you will find these nodes are in Zangarmarsh.  When I went there, I found numerous nodes, in close proximity.

Baradin Fox

Farming this pet took a while, because the Baradin Fox has 64k health and won't die in one shot.  The pet is looted from the Baradin Foxes on the Tol Barad island.  The foxes spawn in 16 spots around the Tol Barad island.  I have marked out 15 of the spawn spots.

This pet took approximately 1400 kills before I finally looted the pet.

Breanni's Pets and Accessories

Breanni is a vendor in Magical Menagerie, located in Dalaran.

She sells 3 pets:

Albino Snake

Calico Cat

Obsidian Hatchling

She also sales accessories to keep your pet happy.  You can buy Happy Pet Snacks, Pet Grooming Kit,  Fetch Ball, Rope Pet Leash and Red Ribbon Pet Leash

Giant Sewer Rat

You can fish up the Giant Sewer Rat in the Underbelly of Dalaran in Northrend. 

I didn't have Rarity (an awesome addon for when you are farming pets) when I caught this little guy, so not sure how many times I had to cast before I caught him, but I do know I spent a lot of time fishing.  I have heard of people catching this pet before their fishing was over 400, so it's possible to level fishing here, and hope for the catch.

Gundrak Hatchling

This grind was rather annoying.  You get the Gundrak Hatchling from killing Gundrak Raptors in Zul'Drak in Northrend.

The raptors respawn at a decent rate, but they are just far enough away that it's quicker to mount up and fly to the next one then to just run to it.  A druid would probably be ideal for this grind.  The raptors are skinnable.  I had problems selling the leather on my server, so check that out on your server.

Disgusting Oozling

I finally made myself sit down and grind this pet.  It didn't take as many kills as I thought.  It took me 1100 kills and 89 bags before I got this beloved pet.

After Cataclysm they increased the drop rate (so I'm told), and changed where you grind them at.   I did my grinding in Swamp of Sorrows.

Farming for this pet is 2 fold.  You must first kill Shifting Mireblobs which swim in the lakes in The Shifting Mire in Swamp of Sorrows.  They have a chance of dropping an Oozling Bag.   You will get the pet from the Oozling Bag.  I seemed to average 1 Oozling Bag for approximately 10 Shifting Mireblob kills.  This grind isn't bad, as the Mireblobs have a fast spawn rate and are close together, so it's constant killing, and not much waiting for respawns.